improve components.md, correct markdown errors, improve javadoc

core/src/main/java/com/spotify/ffwd/AgentCore.java

@@ -378,10 +378,11 @@ protected void configure() {
   /**
    * Reads the configuration of the agent from multiple possible sources. In order of precedence,
    * the following sources are loaded:
-   * - System properties
-   * - Environment variables
-   * - YAML file in specified location
-   * - YAML file bundled with JAR
+   *<p></p>
+   * - System properties<p></p>
+   * - Environment variables<p></p>
+   * - YAML file in specified location<p></p>
+   * - YAML file bundled with JAR<p></p>
    *
    * Values are merged, those higher on this list override those that are lower.
    *

docs/content/_docs/components.md

@@ -6,42 +6,41 @@ title: Components
 
 This document covers some of the major components in FastForward.
 
-#### Module
+![Overview of main FFWD components](./images/ffwd-components.svg "Overview of main FFWD components")
 
-A module is a loadable component that extends the functionality of FastForward.
-When a module is loaded it typically registers a set of plugins.
+## Module
 
-#### Plugin
+A [module](https://github.com/spotify/ffwd/blob/master/api/src/main/java/com/spotify/ffwd/module/FastForwardModule.java) is a dynamically loaded component that extends the functionality of FastForward.
+When a module is [loaded](https://github.com/spotify/ffwd/blob/17de95af58f221ad655dce18515835b2818c7241/core/src/main/java/com/spotify/ffwd/AgentCore.java#L400) it typically [registers a plugin](https://github.com/spotify/ffwd/blob/17de95af58f221ad655dce18515835b2818c7241/modules/pubsub/src/main/java/com/spotify/ffwd/pubsub/PubsubOutputModule.java#L36).
 
-Either an input or an output plugin.
+## Plugin
 
-This provides the implementation to read or send data from the agent.
-A plugin can have multiple _instances_ with different configurations (like
-which port to listen to).
+Either an [input](https://github.com/spotify/ffwd/blob/master/api/src/main/java/com/spotify/ffwd/input/PluginSource.java) or an [output](https://github.com/spotify/ffwd/blob/master/api/src/main/java/com/spotify/ffwd/output/PluginSink.java) plugin.
 
-#### Early Injector
+This provides an implementation which either ingests or emits data from the agent.
 
-The early injector is setup by AgentCore and is intended to provide the basic
-facilities to perform module setup.
+A plugin can have multiple _instances_ with different configurations (like which port to listen to).
+
+## Early Injector
+
+The [early injector](https://github.com/spotify/ffwd/blob/17de95af58f221ad655dce18515835b2818c7241/core/src/main/java/com/spotify/ffwd/AgentCore.java#L212) is setup by AgentCore and is intended to provide the basic facilities to perform module setup.
 
 The following is a list of components that are given access to and their
 purpose.
 
-* _com.spotify.ffwd.module.PluginContext_
+* [_com.spotify.ffwd.module.PluginContext_](https://github.com/spotify/ffwd/blob/master/api/src/main/java/com/spotify/ffwd/module/PluginContext.java)
   Register input and output plugins.
 * _com.fasterxml.jackson.databind.ObjectMapper (config)_
   ObjectMapper used to parse provided configuration file.
 
-#### Primary Injector
+## Primary Injector
 
-The primary injector contains the dependencies which are available after
-modules have been registered and the initial bootstrap is done.
+The [primary injector](https://github.com/spotify/ffwd/blob/17de95af58f221ad655dce18515835b2818c7241/core/src/main/java/com/spotify/ffwd/AgentCore.java#L100) contains the dependencies which are available after modules have been registered and the initial bootstrap is done.
 
 It contains all the components of the early injector, with the following
 additions.
 
-* _eu.toolchain.async.AsyncFramework_ - Framework implementation to use for
-  async operations.
+* _eu.toolchain.async.AsyncFramework_ - Framework implementation to use for async operations.
 * _io.netty.channel.EventLoopGroup (boss)_ Event loop group used for boss
   threads in ServerBootstrap's.
 * _io.netty.channel.EventLoopGroup (worker)_ Event loop group used for